One major criticism of conventional coating compositions is the mess attendant in their handling and application. First, typically, the coating composition must be stirred to redisperse the solids content, and then at least a portion of the coating composition is transferred to a pan adapted to a roller or pad applicator. Splashing, dripping or spilling, prior to and during the actual application of the coating composition to a substrate are always real dangers.
Prior attempts have been made in the art to provide "solid" coating compositions which could be applied in stick form either by manual or machine assisted application, the application shearing force fluidizing the coating composition. However, even in the best of these systems, the gelled, solid or semisolid composition was provided by the use of thixotropic agents, and, while shearing forces could temporarily provide a fluidized system, once the shearing force was removed, the thixotropic agents present once more began to restore the solid nature or gel structure to the system, thus hampering desirable flow and leveling of the applied coating compositions.
In addition, the use of a stick form product entails holding a heavy object up to the application point and increases arm weariness.
Contrary to the prior art systems, in the coating compositions of the invention, once the gel structure formed by the interaction of an electrolyte and a colloidal gelling agent is destroyed by the application of shearing forces, there is little or no recovery of a substantial gel structure contributed by the gelling system. Thus, the compositions of the invention act as conventional paints when coated upon a substrate, providing excellent flow and leveling.
In commonly assigned copending application Ser. No. 912,807, filed June 6, 1978, by James E. Jones et al, now U.S. Pat. No. 4,196,107 there is disclosed compositions identical to the compositions of the invention, but for the presence of the semisolid composition formation rate enhancing compound. These previously disclosed semisolid compositions have excellent application and coating characteristics. However, as stated in said previous application, since the interaction of the colloid and electrolyte frequently requires a substantial period of time at room temperature, in order to obtain a gel structure which is stable within convenient commercial plant production parameters, it is frequently desirable to accelerate the substantially complete interaction between the electrolyte and colloid by the application of heat, for a time sufficient to substantially complete the colloid-electrolyte interaction. As this heating step is most conveniently done after individual market containers have been filled, the mass production of such a product would require substantial unusual additions to a conventional coatings packaging system. The present invention eliminates or reduces the need for such a heat treatment step without substantially altering the other desirable characteristics of the prior disclosed compositions. The present invention also facilitates pre-use (e.g. in retail stores) tinting which could not readily be performed with the heat treated composition.